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 * Copyright (c) 2012, 2014, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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 */

package javafx.scene.control.cell;

import static javafx.scene.control.cell.CellUtils.createChoiceBox;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.scene.control.ChoiceBox;
import javafx.scene.control.Label;
import javafx.scene.control.ListCell;
import javafx.scene.control.ListView;
import javafx.util.Callback;
import javafx.util.StringConverter;

/**
 * A class containing a {@link ListCell} implementation that draws a 
 * {@link ChoiceBox} node inside the cell.
 * 
 * <p>By default, the ChoiceBoxListCell is rendered as a {@link Label} when not 
 * being edited, and as a ChoiceBox when in editing mode. The ChoiceBox will, by 
 * default, stretch to fill the entire list cell.
 * 
 * <p>To create a ChoiceBoxListCell, it is necessary to provide zero or more 
 * items that will be shown to the user when the {@link ChoiceBox} menu is 
 * showing. These items must be of the same type as the ListView items sequence, 
 * such that upon selection, they replace the existing value in the 
 * {@link ListView#itemsProperty() items} list.
 * 
 * @param <T> The type of the elements contained within the ListView.
 * @since JavaFX 2.2
 */
public class ChoiceBoxListCell<T> extends ListCell<T> {
    
    /***************************************************************************
     *                                                                         *
     * Static cell factories                                                   *
     *                                                                         *
     **************************************************************************/
    
    /**
     * Creates a ChoiceBox cell factory for use in {@link ListView} controls. 
     * By default, the ChoiceBoxCell is rendered as a {@link Label} when not 
     * being edited, and as a ChoiceBox when in editing mode. The ChoiceBox will, 
     * by default, stretch to fill the entire list cell.
     * 
     * @param <T> The type of the elements contained within the ListView.
     * @param items Zero or more items that will be shown to the user when the
     *      {@link ChoiceBox} menu is showing. These items must be of the same 
     *      type as the ListView items list, such that upon selection, they 
     *      replace the existing value in the 
     *      {@link ListView#itemsProperty() items} list.
     * @return A {@link Callback} that will return a ListCell that is able to 
     *      work on the type of element contained within the ListView.
     */
    @SafeVarargs
    public static <T> Callback<ListView<T>, ListCell<T>> forListView(final T... items) {
        return forListView(FXCollections.observableArrayList(items));
    }
    
    /**
     * Creates a ChoiceBox cell factory for use in {@link ListView} controls. By
     * default, the ChoiceBoxCell is rendered as a {@link Label} when not being 
     * edited, and as a ChoiceBox when in editing mode. The ChoiceBox will, by 
     * default, stretch to fill the entire list cell.
     * 
     * @param <T> The type of the elements contained within the ListView.
     * @param converter A {@link StringConverter} to convert the given item (of type T) 
     *      to a String for displaying to the user.
     * @param items Zero or more items that will be shown to the user when the
     *      {@link ChoiceBox} menu is showing. These items must be of the same 
     *      type as the ListView items list, such that upon selection, they 
     *      replace the existing value in the 
     *      {@link ListView#itemsProperty() items} list.
     * @return A {@link Callback} that will return a ListCell that is able to 
     *      work on the type of element contained within the ListView.
     */
    @SafeVarargs
    public static <T> Callback<ListView<T>, ListCell<T>> forListView(
            final StringConverter<T> converter, 
            final T... items) {
        return forListView(converter, FXCollections.observableArrayList(items));
    }
    
    /**
     * Creates a ChoiceBox cell factory for use in {@link ListView} controls. 
     * By default, the ChoiceBoxCell is rendered as a {@link Label} when not 
     * being edited, and as a ChoiceBox when in editing mode. The ChoiceBox 
     * will, by default, stretch to fill the entire list cell.
     * 
     * @param <T> The type of the elements contained within the ListView.
     * @param items An {@link ObservableList} containing zero or more items that 
     *      will be shown to the user when the {@link ChoiceBox} menu is showing. 
     *      These items must be of the same type as the ListView items sequence, 
     *      such that upon selection, they replace the existing value in the 
     *      {@link ListView#itemsProperty() items} list.
     * @return A {@link Callback} that will return a ListCell that is able to 
     *      work on the type of element contained within the ListView.
     */
    public static <T> Callback<ListView<T>, ListCell<T>> forListView(
            final ObservableList<T> items) {
        return forListView(null, items);
    }
    
    /**
     * Creates a ChoiceBox cell factory for use in {@link ListView} controls. By 
     * default, the ChoiceBoxCell is rendered as a {@link Label} when not being 
     * edited, and as a ChoiceBox when in editing mode. The ChoiceBox will, by 
     * default, stretch to fill the entire list cell.
     * 
     * @param <T> The type of the elements contained within the ListView.
     * @param converter A {@link StringConverter} to convert the given item (of type T) 
     *      to a String for displaying to the user.
     * @param items An {@link ObservableList} containing zero or more items that 
     *      will be shown to the user when the {@link ChoiceBox} menu is showing. 
     *      These items must be of the same type as the ListView items sequence, 
     *      such that upon selection, they replace the existing value in the 
     *      {@link ListView#itemsProperty() items} list.
     * @return A {@link Callback} that will return a ListCell that is able to 
     *      work on the type of element contained within the ListView.
     */
    public static <T> Callback<ListView<T>, ListCell<T>> forListView(
            final StringConverter<T> converter, 
            final ObservableList<T> items) {
        return list -> new ChoiceBoxListCell<T>(converter, items);
    }
    
    
    
    /***************************************************************************
     *                                                                         *
     * Fields                                                                  *
     *                                                                         *
     **************************************************************************/    
    
    private final ObservableList<T> items;

    private ChoiceBox<T> choiceBox;
    
    
    
    /***************************************************************************
     *                                                                         *
     * Constructors                                                            *
     *                                                                         *
     **************************************************************************/  
    
    /**
     * Creates a default ChoiceBoxListCell with an empty items list.
     */
    public ChoiceBoxListCell() {
        this(FXCollections.<T>observableArrayList());
    }
    
    /**
     * Creates a default {@link ChoiceBoxListCell} instance with the given items
     * being used to populate the {@link ChoiceBox} when it is shown.
     * 
     * @param items The items to show in the ChoiceBox popup menu when selected 
     *      by the user.
     */
    @SafeVarargs
    public ChoiceBoxListCell(T... items) {
        this(FXCollections.observableArrayList(items));
    }
    
    /**
     * Creates a {@link ChoiceBoxListCell} instance with the given items
     * being used to populate the {@link ChoiceBox} when it is shown, and the 
     * {@link StringConverter} being used to convert the item in to a 
     * user-readable form.
     * 
     * @param converter A {@link StringConverter} that can convert an item of type T 
     *      into a user-readable string so that it may then be shown in the 
     *      ChoiceBox popup menu.
     * @param items The items to show in the ChoiceBox popup menu when selected 
     *      by the user.
     */
    @SafeVarargs
    public ChoiceBoxListCell(StringConverter<T> converter, T... items) {
        this(converter, FXCollections.observableArrayList(items));
    }
    
    /**
     * Creates a default {@link ChoiceBoxListCell} instance with the given items
     * being used to populate the {@link ChoiceBox} when it is shown.
     * 
     * @param items The items to show in the ChoiceBox popup menu when selected 
     *      by the user.
     */
    public ChoiceBoxListCell(ObservableList<T> items) {
        this(null, items);
    }

    /**
     * Creates a {@link ChoiceBoxListCell} instance with the given items
     * being used to populate the {@link ChoiceBox} when it is shown, and the 
     * {@link StringConverter} being used to convert the item in to a 
     * user-readable form.
     * 
     * @param converter A {@link StringConverter} that can convert an item of type T 
     *      into a user-readable string so that it may then be shown in the 
     *      ChoiceBox popup menu.
     * @param items The items to show in the ChoiceBox popup menu when selected 
     *      by the user.
     */
    public ChoiceBoxListCell(StringConverter<T> converter, ObservableList<T> items) {
        this.getStyleClass().add("choice-box-list-cell");
        this.items = items;
        setConverter(converter != null ? converter : CellUtils.<T>defaultStringConverter());
    }
    
    

    /***************************************************************************
     *                                                                         *
     * Properties                                                              *
     *                                                                         *
     **************************************************************************/
    
    // --- converter
    private ObjectProperty<StringConverter<T>> converter = 
            new SimpleObjectProperty<StringConverter<T>>(this, "converter");

    /**
     * The {@link StringConverter} property.
     */
    public final ObjectProperty<StringConverter<T>> converterProperty() { 
        return converter; 
    }
    
    /** 
     * Sets the {@link StringConverter} to be used in this cell.
     */
    public final void setConverter(StringConverter<T> value) { 
        converterProperty().set(value); 
    }
    
    /**
     * Returns the {@link StringConverter} used in this cell.
     */
    public final StringConverter<T> getConverter() { 
        return converterProperty().get(); 
    }
    
    
    
    /***************************************************************************
     *                                                                         *
     * Public API                                                              *
     *                                                                         *
     **************************************************************************/
    
    /**
     * Returns the items to be displayed in the ChoiceBox when it is showing.
     */
    public ObservableList<T> getItems() {
        return items;
    }
    
    /** {@inheritDoc} */
    @Override public void startEdit() {
        if (! isEditable() || ! getListView().isEditable()) {
            return;
        }
        
        if (choiceBox == null) {
            choiceBox = createChoiceBox(this, items, converterProperty());
        }
        
        choiceBox.getSelectionModel().select(getItem());
        
        super.startEdit();

        if (isEditing()) {
            setText(null);
            setGraphic(choiceBox);
        }
    }

    /** {@inheritDoc} */
    @Override public void cancelEdit() {
        super.cancelEdit();
        
        setText(getConverter().toString(getItem()));
        setGraphic(null);
    }
    
    /** {@inheritDoc} */
    @Override public void updateItem(T item, boolean empty) {
        super.updateItem(item, empty);
        CellUtils.updateItem(this, getConverter(), null, null, choiceBox);
    }
}
